The present invention relates to a manufacturing technology of a semiconductor device. More particularly, it relates to a technology effectively applicable to manufacturing of an electrically rewritable nonvolatile memory.
In Japanese Unexamined Patent Publication No. 2007-234861 (Patent Document 1), for example, there is described a manufacturing step of a semiconductor device shown in FIGS. 20 to 24 of Patent Document 1. Specifically, over a semiconductor substrate 20, a gate insulation film 34 is formed. Over the gate insulation film 34, a polysilicon film 37 and a cap insulation film 38 are formed (FIG. 20 of Patent Document 1). Then, portions of the cap insulation film 38, the polysilicon film 37, and the gate insulation film 34 in a memory cell formation region are removed (FIG. 21 of Patent Document 1). Then, entirely over the main surface of the semiconductor substrate 20, a gate insulation film 26, an electric charge storage film 27, an insulation film 28, a polysilicon film 29, and a cap insulation film 32 are successively formed (FIG. 22 of Patent Document 1).
Subsequently, in the memory cell formation region, a gate electrode 44 of the memory cell is formed (FIG. 23 of Patent Document 1). Then, in a low breakdown voltage MISFET formation region and a high breakdown voltage MISFET formation region, gate electrodes 39 and 40 are formed, respectively.    [Patent Document 1] Japanese Unexamined Patent Publication No. 2007-234861